OFFSET
0,12
COMMENTS
A companion sequence to A320485.
Digits that appear exactly once in n are erased. Leading zeros are erased unless the result is 0. If all digits are erased, we write -1 for the result (A321797 is another version, which uses 0 for the empty string).
More than the usual number of terms are shown in order to reach some interesting examples.
LINKS
Chai Wah Wu, Table of n, a(n) for n = 0..10000
EXAMPLE
12321 becomes 1221, 1123 becomes 11, 11231 becomes 111, and 100223 becomes 22 (as we don't accept leading zeros). Note that 12345 disappears immediately and we get -1.
PROG
(Python)
def A321800(n):
return (lambda x: int(x) if x != '' else -1)(''.join(d if str(n).count(d) != 1 else '' for d in str(n)))
CROSSREFS
KEYWORD
AUTHOR
Chai Wah Wu, Nov 19 2018
STATUS
approved